Cutterhead unit for hair clipper

ABSTRACT

A cutterhead unit for a hair clipper having a serrated fixed blade, a serrated movable blade engaging upon said fixed blade and adapted to reciprocate in lateral directions relative to said fixed blade, a leaf spring connecting said two blades to each other and guiding the movable blade and also pressing upon it so that it will be pressed against the fixed blade, and screw means for adjusting the positions of the blades relative to each other and for varying the pressure of the leaf spring upon the movable blade.

United States Patent 1 Krayl [451 July 24,1973

CUTTERHEAD UNIT FOR HAIR CLIPPER Inventor: Gerhard Max Krayl, Tuttlingen,

Germany Aeseulabe Werke Aktiengesellschatt vormals Jetter & Scheerer, Tuttlingen, Germany Filed: Aug. 25, 1971 Appl. No.: 174,704

Assignee:

[30] Foreign Application Priority Data Sept. 9, 1970 Germany P 20 44 524.3

US. Cl. 30/221, 30/223 Int. Cl 1326b 19/06 Field of Search 30/210, 221-224 References Cited UNITED STATES PATENTS 2,928,171 3/1960 Oster 30/221 3,052,025 9/1962 Ring 30/224X Primary Examiner0thell M. Simpson Assistant Examiner-Gary L. Smith Attorney-Arthur O. Klein adjusting the positions of the blades relative to each other and for varying the pressure of the leaf spring upon the movable blade.

6 Claims, 4 Drawing Figures CUTTERI-IEAD UNIT FOR HAIR CLIPPER The present invention relates to an electric hair clipper and more particularly to a cutterhead unit for such a clipper.

Such a cutterhead unit generally comprises a fixed serrated base blade, a movable serrated blade which is slidable back and forth across the fixed base blade, and connecting means including at least one leaf spring for resiliently pressing the two blades upon each other. Such a cutterhead unit is usually adapted to be quickly connected to and removed from a clipper body containing a motor for driving the movable blade and also serving as a handle for manipulating the entire machine.

The proper function of such a hair clipper depends primarily upon the pressure with which the movable blade of the cutting unit is pressed upon the fixed blade. If this pressure is too low, the machine will not cut properly since the two blades will then be spread apart by hairs passing between them. If, on the other hand, the two blades are pressed too strongly upon each other, the friction of the movable blade on the fixed blade will be so strong that it will reduce the speed of its motor and thus also the cutting effect of the machine and subject the motor to an excessive load. Furthermore, this strong friction between the surfaces of the two blades which slide along each other also results very soon in an excessive wear upon these surfaces which is far beyond the normal wear which even in a proper operation of the machine tends to reduce the pressure of the blades upon each other. Deviations in the dimensions of the blades of different sets which may occur in their manufacture as well as deviations from the proper shape of the leaf spring may also result in unsuitable contact pressures between the cutting surfaces of the blades.

Consequently, deviations of the proper dimensions may occur which may be due to the manufacture of the blades and the leaf spring and also due to the operation of one of the known machines. These deviations lead to variations of the deflection of the leaf spring and, depending upon the spring characteristic, to smaller or larger deviations of the contact pressure between the blades from the most suitable value.

It is an object of the present invention to connect the two blades of a cutterhead unit adjustably to each other by means of at least one leaf spring so that the contact pressure between the two blades which is produced by this spring may be easily adjusted at any time and, for example, the strength of the leaf spring may also be readjusted if it has been weakened due to aging.

It is another object of the invention to employ the leaf spring for also guiding the movable blade during its reciprocating movements relative to the stationary blade. This also requires the leaf spring to be adjusted to a very particular strength in order to insure a proper function of the cutterhead since this cannot be adequately attained merely by bending the spring during its manufacture so as then to have the proper strength.

A further object of the invention consists in providing a cutterhead unit in which the position of the two blades relative to each other is definitively determined by the leaf spring despite the movable connections be tween the spring and the movable blade and this blade and the fixed blade.

A further object of the invention consists in providing at least'one adjusting screw which connects the fixed lower blade to the leaf spring and acts upon the latter and which is located between the rear edge of the upper movable blade and the downwardly bent rear part of the leaf spring and adjacent to the latter so that by tightening this screw to different extents, it is possible to vary the contact pressure between the two blades to any desired strength.

A further object of the invention consists in providing a cutterhead unit in which one end of the leaf spring forms a crossbar which engages into a guide groove in the movable upper blade, while the other end of the leaf spring is bent downwardly toward the fixed lower blade and the lower edge of this bent end engages into a groove which is provided in the fixed blade or into an element which is adjustably secured to the fixed blade.

By this feature of the invention the result is attained that the crossbar on the front end of the leaf spring engages into the guide groove in the movable upper blade and the lower edge of the downwardly bent rear end of the leaf spring engages into the groove in the fixed blade or in the element which is connected thereto, so that the positions of the two blades relative to each other are definitely determined despite the movable connection between the two blades.

These and additional objects, features and advantages of the present invention will become further apparent from the following detailed description thereof which is to be read with reference to the accompanying drawings, in which FIG. 1 shows a top view of the cutterhead unit according to the invention for an electric hair clipper;

FIG. 2 shows a cross section which is taken along the line II II of FIG. 1;

FIG. 3 shows a cross section which is taken along the line III III of FIG. 1; while FIG. 4 shows a perspective view of the leaf spring of the cutter head unit according to FIG. 1.

Referring to the drawings, FIGS. 1 to 3 illustrate a cutterhead l which may be connected to a conventional electric hair clipper, not shown, by means of a mounting tongue 2. The cutterhead 1 comprises a fixed blade 3 the front edge of which is provided with teeth 4 and which has front and rear sliding surfaces 5. Upon these sliding surfaces 5 of the fixed blade 3 similar front and rear sliding surfaces 6 of a movable blade 7 engage the front edge of which is likewise provided with teeth 8 the free ends of which are offset toward the rear of the free ends of the teeth 4 of the fixed blade at a distance A, as shown in FIG. 1. This distance A and the resulting parallel direction of the front edges of the two blades are of considerable importance for the proper function of the cutter-head l. The movable blade 7 is slidable with a reciprocating motion in a direction parallel to its front edge. This reciprocating motion is produced by a drive mechanism of the clipper, not shown, which acts upon the movable blade 7.

For guiding the movable blade 7 and for pressing it upon the. fixed blade 3, a leaf spring 9 is provided which may, for example, be a stamped part and consist of a suitable spring material. The central part of leaf spring 9 is provided in the usual manner with a large cutout so that two equal parallel arms 10 and 11 are formed which are connected to each other by a crossbar 12 at the front end of the spring. These two spring arms I0 and Il may also be regarded as two individual leaf springs. Crossbar 12 has a substantially V-shaped cross section so that two guide surfaces are formed. On its upper side 13, the movable blade 7 has a V-shaped guide groove 14 which extends substantially parallel to the front edge of this blade and into which the crossbar 12 of leaf spring 9 engages so that the movable blade 7 is guided during its reciprocating movements. The relatively long arms 10 and 11 of leaf spring 9 extend above and separate from the upper side 13 of the movable blade 7 and press the latter resiliently against the fixed blade 3. The end of each arm 10 and 11 of leaf spring 9 opposite to the crossbar 12 is bent substantially at a right angle toward the fixed blade 3 so that the two parts 16 and 17 are formed which act as bracing members. Behind the rear edge of the movable blade 7 leaf spring 9 is indirectly connected to the fixed blade 3, namely, by means of a bar 18 which engages with and is slidable along a surface on the upper side of the fixed blade 3 which extends parallel to the sliding surfaces 5 and 6 of the blades. This bar 18 is provided with two tapped bores 19 and 20 which are spaced from each other and in to which screws and 26 are screwed from the lower side of the fixed blade 3 and through bores 21, 22 and 23, 24 in this blade. Bores 21 and 23 through which the shanks of screws 25 and 26 extend and bores 22 and 24 in which the heads of these screws are located have larger diameters than the shanks or the heads of the screws, respectively, so that when the screws 25 and 26 are loosened, they have a certain clearance in all radial directions in the fixed blade 3 to permit the bar 18 to be adjusted. Bar 18 is provided on its upper side with a pair of grooves 27 and 28 into which the lower edges of the two bent parts 16 and 17 on the rear ends of the arms 10 and 11 of leaf spring 9 engage. Between the bent parts 16 and 17 of arms 10 and 11 and the rear edge 15 of the movable blade 7 two clamping screws 29 and 30 are provided each of which extends through a bore 31 or 32 in the arms 10 and 11, respectively. Each of these bores 31 and 32 is elongated in the direction of the respective arm 10 or 11 so that a certain amount of play exists between each clamping screw 29 and 30 and the arms 10 and 11 of sring 9. Screws 29 and 30 are screwed into tapped bores 33 and 34 in bar 18 which are laterally adjacent to the tapped bores 19 and 20. The fixed blade 3 is provided with blind-end bores 35 and 36 which are in axial alignment with the tapped bores 33 and 34 but have a larger diameter than the latter and are adapted to receive the ends of the clamping screws 29 and 30 if these screws are tightened to such an extent.

FIGS. 1 to 3 illustrate that the pressure with which the movable blade 7 is pressed by leaf spring 9 against the fixed blade 3 may be very accurately adjusted by means of the clamping screws 29 and 30. This has the great advantage that in the production of leaf spring 9 considerable tolerances are admissible insofar as the resilience of this spring is concerned since the force with which the two blades 3 and 7 are pressed against each other depends primarily upon the depth to which the clamping screws 29 and 30 are screwed into the tapped bores 33 and 34 in bar 18. The elasticity constant of leaf sprnng 9 is therefore only of secondary importance. The adjustable mounting of bar 18 on the fixed blade 3 permits this bar together with leaf spring 9 and the clamping screws 29 and 30 to be shifted and thus the distance A in FIG. 1 and also the parallelism between the rows of teeth of the movable and fixed blades to be very accurately adjusted without requiring the clamping screws 29 and 30 to be loosened and the contact pressure between the blades to be newly adjusted. This adjusting movement also does not require any particular knowledge or dexterity and may be carried out by the operator of the clippers. On the other hand, it is possible by very simple means and without affecting the adjustment of the movable blade 7 to vary the contact pressure between the two blades by equally varying the adjustment of both clamping screws 29 and 30. The contact pressure between the blades may be adjusted by the operator according to touch and by observing the operation of the cutterhead, although for a more accurate adjustment which may be equally repeated it is also possible to employ a gauge, not shown, which may be inserted into the gap between the front and rear sliding surfaces 5 and 6 of the two blades 3 and 7 and then engages with the surfaces of both blades within this gap.

Although my invention has been illustrated and described with reference to the preferred embodiment thereof, 1 wish to have it understood that it is in no way limited to the details of such embodiment but is capable of numerous modifications within the scope of the appended claims.

Having thus fully disclosed my invention, what I claim is:

l. A cutterhead unit for an electric hair clipper comprising a fixed blade having a sliding surface and teeth on its front edge, a similar movable blade adapted to reciprocate on said sliding surface in the direction of the front edge of said fixed blade and having a guide groove in its outer side opposite to the side facing said fixed blade, a leaf spring for guiding said movable blade during its reciprocating movements and for pressing said movable blade against said fixed blade, said leaf spring having a relatively long arm extending above and spaced from the upper side of said movable blade and having a crossbar on its free front end engaging into said guide groove of said movable blade, said leaf spring having a part bent downwardly from said arm toward said fixed blade behind the rear edge of said movable blade, and first screw means for connecting said leaf spring to said fixed blade and for varying the pressure of said spring upon said movable blade, said first screw means being located between the rear edge of said movable blade and said bent part of said leaf spring and adjacent to the latter and acting upon said long arm and upon said fixed blade, and a part having a groove carried by said fixed blade, the free edge of said bent part of said leaf spring facing said fixed blade engaging into said groove of said part carried on said fixed plate, said carried part extending substantially parallel to the front edge of said fixed blade.

2. A cutterhead as defined in claim 1, in which said first screw means are screwed into at least one threaded bore in said part carried by said fixed blade containing said groove which is adapted to receive said edge of said bent part of said spring.

3. A cutterhead as defined in claim 1, in which said bent part of said leaf spring extends substantially at a right angle to said long arm of said spring.

4. A cutterhead as defined in claim 1, in which said part carried by said fixed blade containing said groove for receiving said edge of said bent part of said spring forms a bar separate from said fixed blade and located on the side thereof facing said spring and behind the I through said aperture means of said fixed blade and screwed into said bar for securing said bar to said fixed blade, said second screw means when loosened permitting said bar to be shifted in a direction substantially parallel to the front edge of said fixed bar and also substantially at right angles to said direction for adjusting the position of said spring and thus also of said movable blade substantially independently of any adjustment of said first screw means.

5. A cutterhead unit as defined in claim 4, in which said bar is provided with at least one threaded bore into which one of said second screw means is adapted to be screwed, said aperture means being located in said fixed blade in one side thereof facing said bar and having a diameter larger than the. shank of said second screw means, said fixed blade having at least one recess in the other side thereof of a larger diameter than and coaxial to one of said aperture means and terminatng into the same, each of said second screw means having a head within said recess and of diameter larger than the diameter of said aperture means and smaller than the diameter of said recess so that, when said second screw means are loosened, they may be moved in radial directions within said recess and said aperture means.

6. A cutterhead unit as defined in claim 4, in which said long arm of said leaf spring has at least one elongated hole extending in the direction toward said crossbar, said first screw means having a head larger than the narrower width of said hole and a shank extending through said hole and screwed into another threaded bore in said bar.

A UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, in-7, 12 Dated y I: 973

Inventor(s) Gerhard Max Krayl It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the cover sheet item "Aesculabe Werke" should read Aesculap Werke Signed and sealed this l9th day of March 197E.

(SEAL) Attest:

EDWARD M.FLETCHER, JR. C. MARSHALL DANN Attesting Offic er Commissioner of Patents F ORM PO-1 Q50 (10-69) USCOMM-DC 60376-P69 U,S, GOVERNMENT PRINTING OFFICE: 1959 0-366-3Sl, 

1. A cutterhead unit for an electric hair clipper comprising a fixed blade having a sliding surface and teeth on its front edge, a similar movable blade adapted to reciprocate on said sliding surface in the direction of the front edge of said fixed blade and having a guide groove in its outer side opposite to the side facing said fixed blade, a leaf spring for guiding said movable blade during its reciprocating movements and for pressing said movable blade against said fixed blade, said leaf spring having a relatively long arm extending above and spaced from the upper side of said movable blade and having a crossbar on its free front end engaging into said guide groove of said movable blade, said leaf spring having a part bent downwardly from said arm toward said fixed blade behind the rear edge of said movable blade, and first screw means for connecting said leaf spring to said fixed blade and for varying the pressure of said spring upon said movable blade, said first screw means being located between the rear edge of said movable blade and said bent part of said leaf spring and adjacent to the latter and acting upon said long arm and upon said fixed blade, and a part having a groove carried by said fixed blade, the free edge of said bent part of said leaf spring facing said fixed blade engaging into said groove of said part carried on said fixed plate, said carried part extending substantially parallel to the front edge of said fixed blade.
 2. A cutterhead as defined in claim 1, in which said first screw means are screwed into at least one threaded bore in said part carried by said fixed blade containing said groove which is adapted to receive said edge of said bent part of said spring.
 3. A cutterhead as defined in claim 1, in which said bent part of said leaf spring extends substantially at a right angle to said long arm of said spring.
 4. A cutterhead as defined in claim 1, in which said part carried by said fixed blade containing said groove for receiving said edge of said bent part of said spring forms a bar separate from said fixed blade and located on the side thereof facing said spring and behind the rear edge of said movable blade, aperture means in said fixed blade, and second screw means extending through said aperture means of said fixed blade and screwed into said bar for securing said bar to said fixed blade, said second screw means when loosened permitting said bar to be shifted in a direction substantially parallel to the front edge of said fixed bar and also substantially at right angles to said direction for adjusting the position of said spring and thus also of said movable blade substantially independently of any adjustment of said first screw means.
 5. A cutterhead unit as defined in claim 4, in which said bar is provided with at least one threaded bore into which one of said second screw means is adapted to be screwed, said aperture means being located in said fixed blade in one side thereof facing said bar and having a diameter larger than the shank of said second screw means, said fixed blade having at least one recess in the other side thereof of a larger diameter than and coaxial to one of said aperture means and terminatng into the same, each of sAid second screw means having a head within said recess and of diameter larger than the diameter of said aperture means and smaller than the diameter of said recess so that, when said second screw means are loosened, they may be moved in radial directions within said recess and said aperture means.
 6. A cutterhead unit as defined in claim 4, in which said long arm of said leaf spring has at least one elongated hole extending in the direction toward said crossbar, said first screw means having a head larger than the narrower width of said hole and a shank extending through said hole and screwed into another threaded bore in said bar. 